1. Field of the Invention
A container closure integrity system, characterized by a two-component indicator dye/activator combination, which sealingly is mounted within an otherwise conventional cap, and maintained separate from the contents of the container by a non-permeable aperture seal, which conventionally is of aluminum foil. Any opening of the cap will expose the indicator dye/activator combination to evaporate and oxidation effects, thereby physically and chemically altering the appearance of both components and their color, so that replicating the original, sealed condition virtually is impossible.
2. Brief Description of the Prior Art
The present invention is directed to the problem of tampering. A pharmaceutical container, particularly, creates an anxiety in the user, and a need visually to confirm that the container has not been opened, prior to his first use. The present invention has particular utility to the pharmaceutical and foods industry, wherein containers commonly have an aperture closed by a cap, with that aperture initially sealed by a liquid-impermeable material, (typically of aluminum foil), which is bonded to the perimeter of the aperture. The most common response to the problem of tampering has been to define a closure which is believed tamper-proof as a result of the mechanical design of the elements. Such mechanical design techniques have included enclosing the entire container inside of a can with a frangible aluminum top section; using shrink-wrapped seals about the cap and aperture of the container, a cap design which breaks into pieces and various wrapping materials that are destroyed upon removal. The present invention does not interfere with ease of initially opening a conventional cap, rather, an indicator displays a color to represent that the cap has been removed after its initial sealing, and an indicator which easily is visible to the consumer, through an access port designed into a surrounding cardboard package, for example.
Various prior art devices are known wherein a pH sensitive dye is used to illustrate presence or absence of a surrounding gaseous medium, wherein that medium represents a sealed condition of the package. For example, HALPERN, (U.S. Pat. No. 3,899,295) teaches an integrity indicator system for a gas-tight container. A pH sensitive dye is applied to an indicator located within a transparent container, with the activator being a basic, gaseous material that fills the container, and maintains the dye at a color representative of a pH above the slightly acidic pH of 5-7, for normal atmosphere. A related invention HALPERN, (U.S. Pat. No. 4,098,577), illustrates a printed material indicator having a first color in response to the pH of a normal atmosphere, and a second color in response to an acidic gaseous material, which is filled as an artificial atmosphere, within the container.
EARLE, et al., (U.S. Pat. No. 2,537,124), teaches a method for bonding surfaces, where the adhesive composition contains an indicator dye in an alkali suspension, that changes color upon exposure to atmosphere, thereby to correlate the tackiness or condition of dryness of the adhesive. The film forming adhesive composition includes an alkali which is volatile, so that the alkali will evaporate from the adhesive composition, and possibly also oxidize the indicator dye. There is a net reduction in the pH of the adhesive composition thereby rendering a color change, as the adhesive dries. A preferred indicator dye taught by EARLE is phenolphthalein, which is mixed into an adhesive which also contains ammonia as a preferred volatile alkali.
PARKER, (U.S. Pat. No. 2,567,445) teaches a form of cellophane packaging, wherein a transparent material, or a cap, has a semipermeable liner, to allow decomposition effects of the packaged material to contact an indicator dye. The permeable gas changes the color of the dye if the sealed material becomes more basic, for example, upon spoilage.
The present invention also relies upon various indicator dye/activator combinations, which per se are illustrated by the above-discussed prior art. It is well-known that phenolphthalein will exhibit a red color when exposed to an atmosphere having a pH in the vicinity of 9-12, and revert to a colorless condition as the pH environment is reduced, to below 9. The present invention represents improvement, however, in that an otherwise reversible reaction between an indicator dye and an activator structurally is prevented, through a two-component system. The components are structured so that exposure to atmosphere will not only drive off volatiles wetting both components, but also physically alter the absorbent mediums of each compound, as the indicator dye/activator liquid phase solution is being volatized by exposure to air.